242 



SUBMARINE CABLE LAYING AND REPAIRING. 



sheave D S, over a second guide sheave, then takes three or 

 four turns round the winding drum W D, and thence passes 

 over the sheave H S to the tank. The gear receives motion 

 from a small steam engine, -which drives the steam shaft indi- 

 cated in the figure through a speed-reducing gear. 



The drum is only required to run very slowly, at most about 

 twelve revolutions per minute, a considerable amount of pur- 

 chase being obtained by the intermediate train of speed-reducing 



Fig. 140. — Picking-up gear ou Cable Ship " Dacia." 



gear between the drum and the engine. The latter is generally 

 designed to run at 100 to 150 revolutions per minute, and 

 the speed is in some cases reduced by one or two intermediate 

 shafts, with pinions driving spur-wheels, and in others by a 

 large wheel on the first motion-shaft, and a pinion on the 

 engine shaft driving it. The picking-up gear on repairing-ships 

 is designed to lift 25 tons at a speed of 1 nautical mile per 

 hour (about 100 feet per minute), and the set is usually tested 



